The invention relates to power supply circuits and interfaces. More particularly, the invention relates to an interface that allows a device supplying power to determine the amount of current required by a device coupled to the power supply.
Many electronic systems such as computer systems are coupled to receive power via a surge suppressor or other power supply circuit. A surge suppressor is a device that is coupled to provide alternating current (AC) power to electronic devices and prevents damage to the devices as the result of a voltage transient, or voltage spike. Voltage spikes can cause damage to the electronic devices.
Surge suppressors typically include a fuse or breaker switch that cuts power to all of the electronic devices coupled to the surge suppressor in the event of excessive current. One disadvantage to existing surge suppressors (as well as other power supply circuits) is that the addition of a single electronic device can cause the fuse to blow or the breaker to trip, which cuts power to all electronic device coupled to the surge protector or the power supply circuit. Thus, the addition of a single device can cause multiple other devices to cease operating.
For example, a power supply (with or without surge suppression capability) that is used to provide power to rack mounted server modules can be used to provide power for up to 42 server modules in the case of a typical seven foot 42U rack system. If the power supply is only capable of providing power to 40 servers, the addition of the 41st server will cause a fuse to blow or a breaker to trip, which will cut power to all 41 of the server modules. Thus, the addition of a single server module to a rack system can cause many servers to become unavailable for use.